1. Field of the Invention
The invention relates to the field of providing a synthesis technique to grow a film or small wire of gallium nitride on amorphous quartz substrates and on single crystalline substrates such as c-sapphire and polycrystalline substrates.
2. Description of the Prior Art
Gallium nitride (GaN) is a direct, wide band gap semiconductor that finds applications in light emitting diodes (LED), laser diodes (LD), high temperature/power field effect transistors (FET) and UV optical devices. Since both GaN substrates and lattice matched substrates are unavailable, hetero-epitaxy on substrates such as sapphire or SiC is currently employed using metal organic chemical vapor decomposition (MOCVD), Molecular beam epitaxy (MBE) or Hydride vapor phase epitaxy (HVPE) techniques. The lattice mismatch and different thermal expansion coefficients between GaN and substrates cause high density of dislocations and stresses in the film. Lateral Epitaxial Overgrowth (LEO) and Pendeo-epitaxy have achieved significant reduction in the dislocation density, however homoepitaxy on high quality GaN substrates would be preferred.
Bulk gallium nitride growth under high nitrogen pressure (˜kbars) from gallium melt has low dislocation densities (106 cm−2), but the area of these crystals remains at about 3 cm2. Bulk nucleation and growth of GaN from gallium melt at sub atmospheric pressure had been demonstrated using atomic nitrogen. However this process produced epitxial growth on (0001) single crystal sapphire substrate and has dislocation density in excess of 106 μcm−2.